In recent years, as image recording materials, materials particularly for forming color images are predominant and, specifically, recording materials for ink jet systems, recording materials for heat transfer type images, recording materials using electrophotographic systems, silver halide light sensitive materials for transfer type, printing inks and recording pens have been utilized popularity.
In the color image recording materials described above, while coloring materials (dyes or pigments) of three primary colors for so-called subtractive color mixing system have been used for reproducing or recording full color images, coloring materials having absorption characteristics capable of attaining preferred color reproducing regions and which are fast being endurable to various working conditions have not been yet available at present and improvement therefore has been demanded strongly.
Since an ink jet recording method is inexpensive in the material cost, can conduct high speed recording, generates less noises during recording and, further, can conduct color recording easily, the method has been rapidly popularized and has been now under further development.
The ink jet recording method includes a continuous system of flying liquid droplets continuously and an on-demand system of flying liquid droplets in accordance with image information signals, and the ejection system includes a system of applying a pressure by a piezo-element thereby discharging liquid droplets, a system of generating bubbles in an ink by heat thereby discharging liquid droplets, a system of using supersonic waves, or a system of attracting and discharging liquid droplets by electrostatic force. Further, for the ink jet recording ink, an aqueous ink, an oily ink or a solid (hot-melt type) ink is used.
The colorant used for the ink for use in jet recording described above is required that it has good solubility or dispersibility to a solvent, can conduct high density recording, has good hue, fastness to light, heat and active gases in the circumstance (oxidative gas such as NOx and ozone, as well as SOx), has excellent fastness to water or chemicals, good fixing property to image receiving materials with less blur, excellent storability as ink, no toxicity, and high purity and, further, it is available at a reduced cost. However, it is extremely difficult to obtain a colorant capable of satisfying the requirements described above at high level. Particularly, it has been strongly demanded for the colorant that it has favorable hue of three primary colors and is fast to light, humidity and heat and, among all, it is fast to oxidative gases such as ozone in the circumstance upon printing on an image receiving material having an ink receiving layer containing porous inorganic white pigment particles.
Heretofore, azo dyes using phenol, naphthol, aniline, etc. as the coupling ingredient have been used generally as the magenta dye. As azo dyes of favorable hue, those dyes disclosed, for example, in JP-A No. 11-209673 and JP No. 3020660 have been known but they involve a problem of poor light fastness. For improving the problem, dyes having favorable hue and improved with light fastness are disclosed in JP-A No. 2001-335714. However, dyes known in the patent documents described above are extremely poor in view of the fastness to oxidative gases such as ozone.
Further, phthalocyanine dyes and triphenylmethane dyes are typical as cyan dyes.
The phthalocyanine dyes used most generally are typically represented by C.I. Direct Blue 86, 87, and 199 and they have a feature more excellent in the light fastness compared with magenta or yellow dyes. However, they suffer from remarkable change of color or discoloration by oxidative gases such as nitrogen oxide gas or ozone which have often been taken up in view of environmental problems recently.
While JP-A Nos. 3-103484, 4-39365 and 2000-30309, etc. disclose phthalocyanine dyes provided with ozone gas resistance but the effect of improving the fastness to the oxidative gas is extremely insufficient in any of them and a further improvement has been demanded.
On the other hand, while triphenylmethane dyes represented by Acid Blue 9 show favorable hue, they are remarkably poor in the light fastness and ozone gas fastness.
As the yellow dye, azo benzene dyes as represented by Direct Yellow 86 and 120, or heterocyclic ring azo dyes such as pyrazolone azo dye and pyridone azo dye such as Acid Yellow 17 have been used. Further, quinophthalone type dyes have also been often proposed. However, in the dyes known so far, those dyes showing favorable hue and, particularly, sharp cut off on the side of long waves of the absorption spectrum such as quinophthalone dye are often not fast to ozone or light, whereas azo benzene dyes show poor cut off on the side of long waves although favorable in the fastness, and dyes favorable both in the hue and the fastness are not available at present.
Heretofore, while disazo dyes or trisazo dyes have been used for the black dye, since absorption to blue to green light is often insufficient by the use of the dye described above alone, thereby often failing to obtain a good black tone, a color compensation dye for absorbing such blue to green light is generally used together. As the compensation dye, those dyes described, for example, in JP-A No. 9-255906 and JP No. 3178200 specification are proposed and improvement has been attempted for black tone controllability, color forming property, fastness, ink store stability, water proofness and clogging of nozzles.
However, the color compensation dyes proposed so far involve a problem of lacking in the black tone controllability such that a great amount of addition is required because the absorption wavelength is excessively short or other color compensation dye is further required.
Further, while dyes capable of absorbing blue to green lights have generally been known, most of them undergo remarkable change of hue when exposed to light, heat and active gases in the circumstance because of poor fastness, or cause a phenomenon such as yellow blur at the profile portion under high humidity condition because of insufficient fixing property and, further improvement is necessary.
In view of the drawbacks described above, JP-A No. 2002-332426 describes a black ink composition in which a triazine dye having an absorption maximum in a visible region absorption spectrum at 435 nm in an aqueous solvent is blended as a color compensation dye with a black dye.
However, general black dyes have maximum absorption at 570 to 620 nm, and it is apparent that no preferred black tone can be obtained even when the color compensation dye is used in view of the complementary color relation, which is important for the control of the black tone (“Color Science Handbook (second edition)” from University of Tokyo Press, 1998, p560-562).
While JP-A No. 8-302255 describes C.I. Direct Red 84, it does not disclose a black ink composition of combining the same as a short wavelength dye with a long wavelength dye.
JP-A No. 2000-265099 describes C.I. Direct Red 84 in column 8 but this is magenta and it does not disclose a black ink composition using the same as a short wavelength dye in combination with a long wavelength dye.
For obtaining full color images of excellent color reproducibility and having fastness, the following conditions are required for the dye constituting the images:    (1) each of the dyes for three primary colors and black has excellent absorption characteristic,    (2) optimal combination of dyes of three primary colors and black that attains a wide color reproducing region,    (3) each of dyes of three primary colors and black has high fastness,    (4) fastness is not worsened by interaction between dyes,    (5) fastness is balanced between dyes of three primary colors and black.
However, since there are no reports at all regarding the fastness, particularly, the fastness to oxidative gases such as ozone that gives rise to a significant problem in ink jet printing recently, as to what structure or physical property act effectively to the ozone fastness, no guideline for selecting the dyes can be obtained at present. Furthermore, in a case of selecting those having light fastness together, the difficulty is further increased.